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Psychobiology - Midterm 2 > UNIT 2 - NEURONS > Flashcards

UNIT 2 - NEURONS Flashcards

1
Q

What do neurones consist of?

A

Remember: NEURONE IS THE BASIC FUNCTIONAL UNIT OF THE NERVOUS SYSTEM

Cell body, dendrites, axon, and presynaptic terminal.

Also consist of the cell, glia (support cell), neuroglia

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2
Q

Main function of neurone:

A

a) receive and process information from sensory receptors and other neurons
b) send information to the next neuron in the chain of communication or non-neuronal structure (effector organs)

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3
Q

Cell body:

A 
Neuron consists of: 
Cell body (soma) 
Dendrites 
Axon
Presynaptic terminal
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4
Q

Dendrites

A

Synaptic receptors: dendrites receive information from another neuron

Dendritic spine: to increase synapse

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5
Q

Axon

A

> Diameter, carries neural impulse toward other neurons, organ or muscle
Covered in myelin sheath
Nodes of Ranvier
Only one axon

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6
Q

Glia

A

> There are as many glia as neurons

> Does NOT transmit information

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7
Q

Glia (Astrocytes)

A

Astrocyte: wraps around the synapse of functionally related neurons

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8
Q

Other cells of Glia:

  • Microglia
  • Oligodendrocytes
  • Schwann cell
  • Radial Glia
A
  • Microglia:: immune system, removing fungi and viruses in the brain.
  • Oligodendrocytes: CNS
  • Schwann cell: PNS construct the myelin sheath
  • Radial Glia: guide the migration of neurons and their axons during embryonic developement
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9
Q

Ions

A

When electrolytes are dissolved in water, they split into two parts each with an opposing electrical charge

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10
Q

Ions force of act:

A

They move in certain direction > positive and negative it’s called ELECTRICAL POTENTIAL

Force1) Electostatistic pressure: when ions move toward the opposite electrical charge. (e.ie a positive charged ion will move toward areas of negativity)… ALSO CALLED ELECTRICAL GRADIENT

Force 2) DIFFUSION cause ions to move toward are of relatively lower concentration (i.e an ion will go to areas where there are fewer than ions) ALSO CALLED CONCENTRATION GRADIENT

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11
Q

Membrane Potential

A

The difference in electrical charge between the inside of the cell and outside of the cell

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12
Q

Resting Potential

A

DIFFERENCE BETWEEN INSIDE + OUTSIDE : IS RESTING POTENTIAL

Axon membrane is semi-permeable = conducting properties

  • Positive on the outside / Negative on inside
  • Due to unequal ion distribution across membrane
  • Alway -70 millivolts (mV)
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13
Q

Resting Potential - imoportant IONS:

A

Sodium (NA+)
Potassium (K+)
Chloride (CI-)
Calclium (Ca2+)

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14
Q

Resting potential - inside vs outside

A

> There is more Na+ (sodium-) outside, meaning inside is then negative.
At rest more K+ inside.
Equlibrium when only few K+ leave the membrane

> They leak across SODIUM-POTASSIUM PUMP: to ensure that high concentration of Na+ outside of cell and high concentration of K+ is inside of cell.

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15
Q

What keeps negitevly charge protein inside?

A 
Organis onions (A-) = they keep the inside negative 
A- Can't pass through a cell
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16
Q

Chloride Ions:

A

> more outside
want to diffuse inside cell
little movement

17
Q

Hyperpolarisation

A

Negative charge pushes the membrane potential further toward negative

18
Q

Depolarisation

A

A small positive charge become positive. (toward zero mV)

  • but after weak stimulation membrane returns back to resting potential (-70mV)
19
Q

Massive depolarisation:

  • Threshold of excitation
  • Voltage-gate
  • Action Potential
A

When it reaches the threshold,
Ion channel open activating membrane > VOLTAGE-GATE CHANNEL

When it reaches threshold, voltage-gated NA+ channel open causing influx of NA+ - then it shoots up to more positivity, this is ACTION POTENTIAL

20
Q

The All-or-None law

A

All depolarisation when it reaches threshold of excitation

21
Q

Action Potential

A

REVERSED: Inside is positive than outside

22
Q

Repolarisation and Hyper polarisation

A

When the threshold of exciation is reached voltage-gate K+ channel also open

  • K+ opens slightly later and moves more toward negative (given that the inside is positive)
  • K+ takes their positive charge with them

Also, Voltage gate Na+ channel close at the peak of the action potential: Na+ are stopped from entering cell and making it positive

Turning back to negative is REPOLARISATION:
> allow k+ to be open for a while, causing hyperpolarisation: more negative than it was during resting potential
> K+ channels close again > Goes to resting potential
By the help of sodium-potassium pump.

23
Q

Refractory Period

A

After repolarising, the cell is less likely to produce another action potential, that is REFRACTORY PERIOD

Absouloute refractory period: impossible to produce another action (1-2 ms)

Relative refractory period: needs larger stimulation than normal to produce action potential (2-3ms)

24
Q

Propagation of Action Potential

A

Na+ flow inside the axon to the neighboring areas of negativity

  • does not go backward
25
Q

Saltatory Conduction

A

When Na+ goes to one of nodes of ranviar to the other one (salta=jump)

Effecient because:

  • It speeds up propergation of action potential
  • Maintains strength of the neural impulse
  • Conserves energy
26
Q

Multiple sclerosis

A

Immune system that attacks myelin sheat (autoimmune disease)

27
Q

The synapse

A

Gap or junction bewteen neuron allowing them to communicate

  • Communcation: PRE-SYNAPTIC
  • Recieving: POST-SYNAPTIC

Light stimulation of PRE > depolorises > POST: GRADED POTENTIAL

28
Q

EPSPs VS IPSPs

A

EPSPs
> DEPOLARISATION IS AN EXCIATORY POSTSYNAPTIC POTENTIAL
>NA+ to POSTsynaptic membrane
> Increase the postsynaptic to fire

IPSPs:
> INHIBITORY POST SYNAPTIC POTENTIAL:
> WHEN PRESYNAPTIC neuron cause hyperolatisation to POST
> Decrease the postsynaptic to fire

So it all comes down which neuron fires is determined by

29
Q

TEMPORAL SUMMATION VS SPATIAL SUMMATION

A

Temporal summation: EPS adding depolorasation to another EPSP

Spatial summation: when several presynaptic neuron stimulate a postsynaptic neuron

30
Q

Loewl (1920)

A

Frogs release chemical of: neurotransmitters

31
Q

Neurotransmitter synhesis: GABA VS GLUTAMATE

A

Most synaptic communcation is done by Glutamate (excitatory) and GABA (inhibitory)
> both amino acid in neurotransmitter

32
Q

Neurotransmitter released

A

Action potential travel down axon to the presynaptic terminal where they activate:
VOLTAGE-GATE CALCIUM (CA2+) channel causing and influx of CA2+

33
Q

Removal of neurotransmitter

A

Achethycholine is broke down into inactive fragment (acetate and choline) by ACETHYCHOLINSTERASE

34
Q

REPUTAKE

A

Not broken neurotransmitter, but rather reabsourbed

35
Q

Negative feedback to presynaptic neurone for limit of neurotransmitter: two ways

A

1) PREsynap realese neurotransmitter and inhibit synthesis
2) POSTsynap release chemical, travel back to pre to inhibit any release of neurotransmitter

AFTER SYNAPTIC, NEUROTRANSMITTER MUST BE REMOVED

Psychobiology - Midterm 2 (5 decks)

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